Refer to the individual attribute's documentation for information on default parameter values. In this case, both named parameters default to false, so they can be omitted. The first parameter, the DLL name, is positional and always comes first the others are named. For example, these three attributes are equivalent: Positional parameters are specified first. Any positional parameters must be specified in a certain order and cannot be omitted named parameters are optional and can be specified in any order. Many attributes have parameters, which can be positional, unnamed, or named. For example, is equivalent to, but DllImportAttribute is the attribute's actual name in the. However, you do not need to specify the attribute suffix when using attributes in code. An example of such a multiuse attribute is ConditionalAttribute: īy convention, all attribute names end with the word "Attribute" to distinguish them from other items in the. Some attributes can be specified more than once for a given entity. More than one attribute can be placed on a declaration: Imports
' Objects of this type can be serialized.Ī method with the attribute DllImportAttribute is declared like this: Imports In this example, the SerializableAttribute attribute is used to apply a specific characteristic to a class: Public Class SampleClass It must appear immediately before the element to which it is applied, on the same line. In Visual Basic, an attribute is enclosed in angle brackets (). For more information, see Accessing Attributes by Using Reflection (Visual Basic).Īttributes can be placed on most any declaration, though a specific attribute might restrict the types of declarations on which it is valid. Your program can examine its own metadata or the metadata in other programs by using reflection. You can apply one or more attributes to entire assemblies, modules, or smaller program elements such as classes and properties.Īttributes can accept arguments in the same way as methods and properties. For more information, see, Creating Custom Attributes (Visual Basic). You can add custom attributes to specify any additional information that is required. NET assemblies contain a specified set of metadata that describes the types and type members defined in the assembly. Metadata is information about the types defined in a program. For more information, see Reflection (Visual Basic).Īttributes have the following properties:Īttributes add metadata to your program. After an attribute is associated with a program entity, the attribute can be queried at run time by using a technique called reflection.
#Visual basic net properties code#
Attributes provide a powerful method of associating metadata, or declarative information, with code (assemblies, types, methods, properties, and so forth).